CMPS 160 -- Spring 2013

CMPS 160 -- Programming Assignment 2 (shader graphics)

Due date:
12 midnight, Friday, 5/3/12

Objectives:

This assignment covers the following components: normal calculations, lighting, diffuse and specular reflections, and shaders

Description:

This assignment will enhance your fractal terrain program. In program 1, your fractal terrain was rendered as a wireframe. In this program, you will get to add "skin" or surface to the terrain.

Requirements:

10% of functionality: Combine lab3 and lab4 so that you can render your fractal terrain using ambient lighting or flat shading. Add GUI to allow user to switch between the two.
30% of functionality: Implement smooth shading. With flat shading (from lab4) you can see individual triangles when you look closely. If we want to create an illusion of a smooth surface, we can do so without adding geometry, but simply fooling the eyes with smooth shading. Smooth shading works by assigning a color to each vertex (rather than each polygon), and interpolating the vertex colors. To do this, you need to calculate a vertex normal (which is averaged from adjacent surface normals sharing that vertex). The perceived color due to diffuse reflections at the vertices is calculated in the same manner as the method used for the polygon faces. This is called smooth or Gouraud shading. Be sure to update your GUI so that users can switch among the different lighting options.
40% of functionality: Aside from diffuse reflections, you can make the fractal terrain appear shiny including specular reflections. Specular reflections will very over the terrain depending on the relationships between the surface normal, light direction, and eye direction. You can use the Halfway Vector approach. Include option to turn specular reflections on or off in your GUI. Note that it's possible to have flat shading with specular reflections also. That is, lighting calculations (ambient, diffuse or specular) is independent from shading calculations (flat or smooth).
20% of functionality: Instead of having the entire terrain have the same color (but different shading), vary the color of the terrain by elevation. For example, lower elevation could be green to represent vegetation. Mid-elevations would be brown, while higher elevation could be white. You will probably want to include some element of randomness so your terrain doesn't end up looking like some weird 3-layer cake. Note that this functionality is independent of lighting calculations. That is, you can turn this height-based coloring on or off independently of whether you are using constant or smooth shading.
10% bonus: You can earn some bonus points (in addition to early bonus points) if you implement Phong shading. This requires interpolating vertex normals and calculating normals at every point on the polygon.

Resource:

Here's some info about diffuse shading.
Also read chapter 5 of your textbook, and study the examples in that chapter as well.
Finally, here's a GLSL reference manual

Grading:

This program nominally accounts for 8% of your final grade. We must be able to compile/test your code. Make sure that the code and accompanying make/project files, etc. are tested for successful compilation at least on the PCs in the lab. Also be sure to include the statically linked executable and a README file in your submission as to which platform to use. Programs turned in at least a full day early will earn 1% bonus credit. Late programs will be charged a 1% late point. In addition, late programs will not be accepted 24 hours past due date. The bonus credits may be accumulated up to a total of 50% toward program and final project credits. Programs are graded 80% for functionality and correctness and 20% for style, readability, documentation/writeup, and efficiency. Additional points may also be earned for extra features.

Submission:

Submission must be done using the "submit" command from CATS.

submit cmps160-ap.s13 prog2 prog2.tar, or
submit cmps160-ap.s13 prog2 prog2.zip

This command should work from unix.ic.ucsc.edu. Create and submit a subdirectory called prog1. It should contain a statically linked executable and all the files you have to make your program compile/run. Tar or zip up prog1 before submitting.